a) Field of the Invention
The present invention relates to a surgical microscope apparatus which comprises a microscope and a supporting device for supporting the microscope in a shiftable manner.
b) Description of the Prior Art
A microscope apparatus to be used for microsurgery generally consists of a microscope which permits observation of a part to be operated on, and a supporting device which permits shifting the microscope to desired locations and sustaining the microscope at the locations. A variety of apparatus' have hitherto been made for the supporting device so that it can provide the desired visual fields for an operator through simple handling procedures during surgical operations.
Japanese Patent Preliminary Publication No. Sho 53-23168, for example, discloses a supporting device as shown in FIG. 1 wherein a turning moment of a microscope M is balanced with that of balancing weights Ga and Gb, and a shifting mechanism for the microscope M is fixed by using an electromagnetic lock attached to bearings BL1 through BL6. This supporting device permits an operator to shift the microscope M to a desired angle and a desired location by exerting a very weak force, and hold the microscope M in this state.
Furthermore, Swiss Patent No. 482 439 discloses a supporting device which is configured so as to permit electrically shifting a microscope by using control members disposed on a head rest. This supporting device makes it possible for an operator to shift the microscope without using his hands.
Furthermore, Japanese Patent Preliminary Publication No. Sho 61-172552 proposes a supporting device which detects a direction of a line of vision of an observer within an observing visual field and controls a microscope shifting means on the basis of a result obtained by the detection so that a center of an object to be observed which is located in the direction of the line of vision is coincident with a center of the observation visual field of a microscope. This supporting device makes it possible for an operator to shift the microscope to a desired location simply by changing a direction of vision of the operator.
The supporting device disclosed by Japanese Patent Preliminary Publication No. Sho 53-23168 obliges an operator to use his hand for shifting the microscope M and forces him to interrupt a surgical operation when he requires to shift the microscope during the surgical operation. In such a case, it is necessary to take measures for interrupting the surgical operation and such interruption at a serious step of a surgical operation may be fatal to the life of a patient.
A supporting device of the type disclosed by Swiss Patent No. 482 439 is configured so as to operate the control members by using a head of an operator and permit shifting a microscope without interrupting a surgical operation. When the microscope is set at a high magnification level, however, the microscope has a small diameter of an observing pupil and a slight deviation of an eye of an operator from an eyepiece lens may cause a loss of sight of an observation visual field, thereby constituting a danger for a patient.
Moreover, the supporting device disclosed by Japanese Patent Preliminary Publication No. Sho 61-172552 is effective to shift a microscope for observing a part to be operated on which is located within an observation visual field, but obliges an operator to direct his line of vision continuously outside the visual field when the microscope is to be shifted to a part to be operated which is located outside the visual field, thereby requiring a rather long time for shifting the microscope, having a tendency to tire an operator and therefore not being suited for practical use.